Variable rewards, instantaneous short-form tailored content, fear of missing out. It's carefully built for continuous user engagement.
Algo recs and reels nearly killed IG for me. It desperately tries to become TikTok but that's not why I signed up for IG (which was photos). Photos still exist, but even if you like every photo and "dislike" every reel for months it will still push 99% reel content in your feed--whatever ML they use has been near totally useless.
That is literally their default mode. They had to introduce a "For You" feed (hidden behind a tap on Instagram logo) to go around EU regulations.
Instagram's default feed is an abomination. For me it shows two posts from people I follow, and then an endless stream of ads and "suggested" content.
Thankfully I don't engage with Instagram much, and a few years back I muted/unfollowed a bunch of people, so the algorithmic feed is mostly okay: dogs, cats, climbing. But most of it is recycled regurgitated aggregator accounts
You pretty much only see instagram content when you visit a specific person’s page and that’s all you will ever see.